The advent of clinical trials in spinal muscular atrophy (SMA) has highlighted the need to define patterns of progression using functional scales. It has recently been suggested that the analysis of abilities gained or lost applied to functional scales better reflects meaningful changes. We defined as "gain" a positive change between scores from 0 to either 1 or 2 and as "loss" a negative change from either 2 or 1 to 0. The aim of this study was to describe, over 12 months, which abilities on the Hammersmith Functional Motor Scale Expanded (HFMSE) were more frequently lost or gained in patients with SMA II. The cohort included 614 12-month assessments from 243 patients (age range: 30 months - 63 years; mean 9.94, SD ±7.91). The peak of abilities gained occurred before the age of 5 years while the highest number of lost abilities was found in the group 5-13 years. A correlation between the HFMSE baseline score and the ordinal number of the items was found for both lost (p<0.001) or gained (p<0.001) activities. No correlation was found with SMN2 copy number. These findings will have implications for clinical trial design and for the interpretation of real-world data using new therapeutic approaches.

中文翻译：

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II 型 SMA 能力的获得和丧失：一项为期 12 个月的自然史研究

脊髓性肌萎缩症 (SMA) 临床试验的出现凸显了使用功能量表定义进展模式的必要性。最近有人建议，将能力获得或损失应用于功能量表的分析更好地反映了有意义的变化。我们将分数从 0 到 1 或 2 之间的正变化定义为“获得”，而从 2 或 1 到 0 的负变化定义为“损失”。本研究的目的是在 12 个月内描述哪些能力Hammersmith 扩展功能运动量表 (HFMSE) 在 SMA II 患者中丢失或增加的频率更高。该队列包括来自 243 名患者的 614 次 12 个月评估（年龄范围：30 个月 - 63 岁；平均 9.94，SD ±7.91）。获得能力的高峰出现在 5 岁之前，而失去能力的人数最多的是 5-13 岁。发现 HFMSE 基线评分与项目序号之间的相关性对于丢失 (p<0.001) 或获得 (p<0.001) 的活动。未发现与 SMN2 拷贝数相关。这些发现将对临床试验设计和使用新治疗方法解释真实世界数据产生影响。